Metrohm 820 IC Separation Center - Manual (Page 75)

4.1 Practical notes on ion chromatography
819 IC Detector / 820 IC Separation Center
67
Storage
Always store the separating columns closed when not in use and filled
in accordance with the manufacturer’s specifications.
Dead volume
Dead volume at the end of a column can be the cause of extreme peak
broadening or splitting (appearance of double peaks). Filling the col-
umn with glass beads ( ∅ ≤ 100 µ m) frequently improves the separation
efficiency.
Regeneration
If the separation properties of the column have deteriorated, it can be
regenerated in accordance with the column manufacturer’s specifica-
tions. With the separating columns available from Metrohm (see
Metrohm’s “Range of IC columns”), the instructions for regeneration
can be found on the leaflet enclosed with every column.
In the case of separating columns with carrier material based on sil-
ica, only solutions with pH 2 … 7 may be used for regeneration,
otherwise the columns could be damaged.
4.1.2 Pumps
Pulsation dampener
For sensitive measurements with the 819/820 IC System, high pressure
pumps as free from pulsation as possible and with a very constant ca-
pacity are required. If the pulsations that appear are too large, a pulsa-
tion dampener between the pump and the 820 IC Separation Center
may possibly help. The optional 6.2620.150 Pulsation dampener
(see Section 6.3.1), whose installation is described in Section 2.7.2 is
eminently suitable for this purpose. A pulsation dampener also offers
protection against pressure shocks on the column material caused by
injection.
Maintenance
To protect the pump against foreign particles, we advise you to subject
the eluent to microfiltration (0.45 µ m filter) and siphon the eluent
through the 6.2821.090 Aspirating Filter.
In many cases, an unstable baseline (pulsation, flow fluctuations) can
be traced to contaminated valves or faulty, leaky piston seals.
Contaminated valves are cleaned by rinsing with water, RBS solution
or organic solvents. The rinsing effect is improved by brief treatment in
an ultrasonic bath. When the cleaned valves are reinstalled, you must
ensure that the flow direction is correct.
The replacement of piston seals has to be done in accordance with
the pump manufacturer’s directions. The corresponding maintenance
work for the 818 IC Pump is described in Section 4.2 of the 818 Instruc-
tions for Use.
Salt crystals between the piston and the seal are the cause of abrasive
particles, which can enter the eluent. These lead to contaminated